To bevel a tube means to reduce or to slim down the wall thickness of this tube at its edges. This needs to be done when the wall thickness is of more than 3 millimetres and allows therefore to prepare the assembly of the tubes/accessories.
How must the bevels be prepared?
When you proceed to a TIG welding of tubes with wall thicknesses of more than 3 millimetres, an orbital welding without bevel is generally not possible.
The TIG welding equipment needs too much power in order to proceed to a fusion of metal without a bevel. You also have to meet the existing European / Asian / American … standards for the tubes that you wish to assemble.
The characteristics of the tube are very important as they might have concerns regarding particular standards for its diameter and thickness.
Another important issue is the basic material of the tube and the standards that indicates the values in “inches” or “millimetres”. Beside the special orbital beveling machines dedicated to this kind of applications, other mechanical processes can be used:
- machining centres
- grinding machines
- water jet
- laser systems
What are the advantages and disadvantages of theses processes?
All these systems reduce wall thickness and therefore take off some of the material. The different processes (machining centre, limes, grinding machines, flames, water jet and laser) affect the quality of the tubes, and cause risks for the operators and the environment.
In addition to this they are time consuming. According to the size of the tube and its length, an important work area is often required – for the use of a machining centre for example.
In fact, the tube rotates on its own whilst the tool takes off some material. Special tubes are needed and a very specialized mechanic is necessary, in addition to the necessary workplace.
- The grinding machine uses an abrasive disk, which rotates very quickly (1800 turns per minute). This heats the material, denatures it and modifies the chemical composition. Dust will be generated and the atmosphere will be polluted.
- The lime is an abrasive and pollutant friction tool. The altered tubes will be difficult to weld afterwards.
As regards the other processes that are potentially risky for the operators, the use of a flame in order to melt part of the thickness that has to be removed. The risk is self-explanatory by the use of the gas flame.
- Gas flames are often used when it comes to prepare tubes with wall thicknesses of more than 20 millimetres and can easily go up to wall thicknesses of 60 or 120 millimètres. In the same way, using a laser system for beveling is tedious, as important machinery is needed. Additionally, special protection equipment for the operators working close to the machine is necessary.
- Another solution: using water jet. The jet is concentrated and becomes very powerful, thus, able to cut the material. The implementation of such a system is also tedious and sometimes complicated for certain types of industries. This process can be used for metal sheet cutting, bending or forming.
Which beveling system should be preferred according to the diameter of the tube?
Considering all beveling technologies, there is only one that will be easy to handle by the operators with high production rate. The implementation of an orbital beveling machine in a production site is very easy and certainly the best choice.
Regardless if it is used for helping to build a new tube installation, or in the case of maintenance of former installations, the orbital beveling machine will be the most effective solution.
Depending of the tubes’ diameters, orbital beveling is the best choice even if only very limited space is available.
Orbital beveling is part of the global process that includes the orbital cutting before the beveling process and the orbital welding at the end. Find out more about TIG welding in this free handbook!